Add a check to the release workflow to abort if docs or schema are not up to date

Of course it would be cooler if the workflow could create the PR and merge it if
necessary, but this will have to do for now.

Author: stefanhaller

.github/workflows/release.yml

@@ -70,6 +70,15 @@ jobs:
             exit 1
           fi
 
+      - name: Check that docs and schema are up to date
+        run: |
+          if diff -r -q docs docs-master > /dev/null && diff -r -q schema schema-master > /dev/null; then
+            echo "Docs and schema are up to date."
+          else
+            echo "Docs or schema are out of date. Please run 'scripts/update_docs_for_release.sh' and make a PR."
+            exit 1
+          fi
+
       - name: Check for Blocking Issues/PRs
         if: ${{ !inputs.ignore_blocks }}
         id: check_blocks